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the periodic eclipses of the pre - main - sequence binary, kh 15d, have been explained by a circumbinary dust ring inclined to the orbital plane, which causes occultations of the stars as they pass behind the ring edge. we compute the extinction and forward scattering of light by the edge of the dust ring to explain ( 1 ) the gradual slope directly preceding total eclipse, ( 2 ) the gradual decline at the end of ingress, and ( 3 ) the slight rise in flux at mid - eclipse. the size of the forward scattering halo indicates that the dust grains have a radius of a ~ 6 ( d / 3 au ) microns, where d is the distance of the edge of the ring from the system barycenter. this dust size estimate agrees well with estimates of the dust grain size from polarimetry, adding to the evidence that the ring lies at several au. finally, the ratio of the fluxes inside and outside eclipse independently indicates that the ring lies at a few astronomical units.
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arxiv:0803.4275
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we study properties of ( bi - infinite ) arrays having all adjacent $ k \ times k $ adjacent minors equal to one. if we further add the condition that all adjacent $ ( k - 1 ) \ times ( k - 1 ) $ minors be nonzero, then these arrays are necessarily of rank $ k $. it follows that we can explicit construct all of them. several nice properties are made apparent. in particular, we revisit, with this perspective, the notion of frieze patterns of coxeter. this shed new light on their properties. a connexion is also established with the notion of $ t $ - systems of statistical physics.
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arxiv:1002.1089
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the bead process is the particle system defined on parallel lines, with underlying measure giving constant weight to all configurations in which particles on neighbouring lines interlace, and zero weight otherwise. motivated by the statistical mechanical model of the tiling of an $ abc $ - hexagon by three species of rhombi, a finitized version of the bead process is defined. the corresponding joint distribution can be realized as an eigenvalue probability density function for a sequence of random matrices. the finitized bead process is determinantal, and we give the correlation kernel in terms of jacobi polynomials. two scaling limits are considered : a global limit in which the spacing between lines goes to zero, and a certain bulk scaling limit. in the global limit the shape of the support of the particles is determined, while in the bulk scaling limit the bead process kernel of boutillier is reclaimed, after approriate identification of the anisotropy parameter therein.
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arxiv:0902.0709
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we have measured phosphorus abundances in nine disk stars between - 1 $ < $ [ fe / h ] $ < $ - 0. 5 and in 12 members of the hyades open cluster using two p i lines at 1. 06 $ \ mu $ m. high resolution infrared spectra were obtained using phoenix on gemini south and abundances were determined by comparing synthetic spectra to the observations. the average abundance for the dwarf stars in our hyades sample was $ < $ [ p / fe ] $ > $ = - 0. 01 $ \ pm $ 0. 06 and $ < $ [ p / fe ] $ > $ = 0. 03 $ \ pm $ 0. 03 dex for the three giants. the consistency suggests abundances derived using the 1. 06 $ \ mu $ m p i lines are not subjected to temperature or luminosity dependent systematic effects at high metallicities. our [ p / fe ] ratios measured in disk stars are consistent with chemical evolution models with p yields increased by a factor of 2. 75. we find [ p / o ], [ p / mg ], [ p / si ] and [ p / ti ] ratios are consistent with the solar ratio over a range of - 1. 0 $ < $ [ fe / h ] $ < $ 0. 2 with the [ p / si ] ratio increasing by $ \ sim $ 0. 1 - 0. 2 dex at the lowest [ fe / h ] ratios. finally, the evolution of [ p / fe ] with age is similar to other $ \ alpha $ elements, providing evidence that p is produced at the same sites.
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arxiv:1910.00044
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the textile industry is searching for innovative production techniques to improve the product quality, as well as society requires new finishing techniques working in environmental respect. plasma surface treatments show distinct advantages, because they are able to modify the surface properties of inert materials, sometimes with environment friendly devices. for fabrics, cold plasma treatments require the development of reliable and large systems. such systems are now existing and the use of plasma physics in industrial problems is rapidly increasing. on textile surfaces, three main effects can be obtained depending on the treatment conditions : the cleaning effect, the increase of microroughness ( anti - pilling finishing of wool ) and the production of radicals to obtain hydrophilic surfaces. plasma polymerisation, that is the deposition of solid polymeric materials with desired properties on textile substrates, is under development. the advantage of such plasma treatments is that the modification turns out to be restricted in the uppermost layers of the substrate, thus not affecting the overall desirable bulk properties. here, we present the research results on the use of plasma physics in textile properties modification. treatments on natural, wool and cotton, and on synthetic polymers to improve wetting are shown. hydrophilic - hydrophobic treatments, dirt - repellent coatings are presented. low - pressure and atmospheric - pressure glow discharge systems are also discussed.
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arxiv:0801.3727
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we present a unique method that allows the lsst to scan the sky for stellar variability on short timescales. the operational component of the strategy requires lsst to take star trail images. the image processing component uses deep learning to sift for transient events on timescales down to 10 ms. we advocate for enabling this observing mode with lsst, as coupling this capability with the lsst ' s tremendous 319. 5 m $ ^ 2 $ deg $ ^ 2 $ etendue will produce the first wide area optical survey of the universe on these timescales. we explain how these data will advance both planned lines of investigation and enable new research in the areas of stellar flares, cataclysmic variables, active galactic nuclei, kuiper belt objects, gamma - ray bursts, and fast radio bursts.
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arxiv:1812.02932
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let $ f ( x, y ), g ( x, y ) $ denote either a pair of holomorphic function germs, or a pair of monic polynomials in $ x $ whose coefficients are laurent series in $ y $. a relative polar arc is a newton - puiseux root, $ x = \ gamma ( y ) $, of the jacobian $ j = f _ yg _ x - f _ xg _ y $. we define the tree - model, $ t ( f, g ) $, for the pair, using the contact orders of the newton - puiseux roots of $ f $ and $ g $. we then describe how the $ \ gamma $ ' s climb, and where they leave, the tree. we shall also show by two examples that the way the $ \ gamma $ ' s leave the tree is not an invariant of the tree ; this phenomenon is in sharp contrast to that in the one function case where the tree completely determines how the polar roots split away. our result yield a factorisation of the jacobian determinant.
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arxiv:math/0211408
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, saudi arabia, scotland ( honours degree ), serbia ( three or four years ), spain, south africa ( fourth year is elective — to obtain an honours degree, which is normally a requirement for selection into a master ' s degree program ), south korea, sri lanka ( three, four, or five ( specialized ) years ), taiwan, tajikistan ( four or five years ), thailand, turkmenistan ( four years ), tunisia ( only a bachelor of science in business administration is available, solely awarded by tunis business school ), turkey, ukraine, the united states, uruguay ( four, five, six, or seven years ), vietnam ( four or five years ), yemen, and zambia ( four or five years ). = = = five years = = = canada ( except quebec, four or five years ), cuba ( five years ), greece ( four or five years ), peru, argentina, colombia ( five years ), brazil ( four or five years ), mexico ( four or five years ), chile ( five or six years ), venezuela ( five years ), egypt ( four or five years ), haiti ( four or five years ), iran ( four or five years ), the philippines ( four or five years ). bangladesh ( four or five years ), pakistan ( four or five years ), indonesia ( four or five years ), nigeria ( four or five years ), six months dedicated to siwes ( students industrial work exchange scheme ) but for most sciences and all engineering courses only. a semester for project work / thesis not excluding course work during the bachelor thesis. excluding one year for the compulsory national youth service corps ( nysc ), para - military and civil service. north macedonia, sierra leone ( four years dedicated to coursework ), slovenia ( four or five years ), sudan ( five years for bsc honours degree and four years for bsc ordinary degree ), and syria. in algeria, the student presents a thesis in front of a jury at the end of the fifth year. some universities in canada ( such as university of british columbia and vancouver island university ) have most of their science and applied science students extend their degree by a year compared to other institutions. = = = six years = = = in chile, some undergraduate majors such as engineering and geology are designed as six - year programs. however, in practice it is not uncommon for students to complete such programs over the course of ten years, while studying full - time without leaves of absence. this is in part due to a strict
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https://en.wikipedia.org/wiki/Bachelor_of_Science
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the covid - 19 pandemic continues to spread and impact the well - being of the global population. the front - line modalities including computed tomography ( ct ) and x - ray play an important role for triaging covid patients. considering the limited access of resources ( both hardware and trained personnel ) and decontamination considerations, ct may not be ideal for triaging suspected subjects. artificial intelligence ( ai ) assisted x - ray based applications for triaging and monitoring require experienced radiologists to identify covid patients in a timely manner and to further delineate the disease region boundary are seen as a promising solution. our proposed solution differs from existing solutions by industry and academic communities, and demonstrates a functional ai model to triage by inferencing using a single x - ray image, while the deep - learning model is trained using both x - ray and ct data. we report on how such a multi - modal training improves the solution compared to x - ray only training. the multi - modal solution increases the auc ( area under the receiver operating characteristic curve ) from 0. 89 to 0. 93 and also positively impacts the dice coefficient ( 0. 59 to 0. 62 ) for localizing the pathology. to the best our knowledge, it is the first x - ray solution by leveraging multi - modal information for the development.
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arxiv:2011.05186
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charge transfer states in organic semiconductors play crucial roles in processes such as singlet fission and exciton dissociation at donor / acceptor interfaces. recently, a time - resolved spectroscopy study of dinaphtho [ 2, 3 - b : 2 ' 3 ' - f ] thieno [ 3, 2 - b ] - thiophene ( dntt ) thin films provided evidence for the formation of mixed frenkel and charge - transfer excitons after the photoexcitation. here we investigate optical properties and excitation dynamics of the dntt thin films by combining ab initio calculations and a stochastic schrodinger equation. our theory predicts that the low - energy frenkel exciton band consists of 8 to 47 % ct character. the quantum dynamics simulations show coherent dynamics of frenkel and ct states in 50 fs after the optical excitation. we demonstrate the role of charge delocalization and localization in the mixing of ct states with frenkel excitons as well as the role of their decoherence.
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arxiv:1602.05678
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in this paper, we show that every pair of absolutely compatible hilbert space effects are coexistent and exhibit a partial orthogonality property. we introduce the notion of partially ortho - coexistence. we generalize absolute compatibility to obtain more examples of partially ortho - coexistent pairs and introduce the notion of generalized compatibility. in the case of $ \ mathbb { m } _ 2 $, we discuss a geometric behaviour of the generalized compatibility.
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arxiv:2411.08445
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we consider spacetime to be a connected real 4 - manifold equipped with a lorentzian metric and an affine connection. the 10 independent components of the ( symmetric ) metric tensor and the 64 connection coefficients are the unknowns of our theory. we introduce an action which is quadratic in curvature and study the resulting system of euler - lagrange equations. in the first part of the paper we look for riemannian solutions, i. e. solutions whose connection is levi - civita. we find two classes of riemannian solutions : 1 ) einstein spaces, and 2 ) spacetimes with metric of a pp - wave and parallel ricci curvature. we prove that for a generic quadratic action these are the only riemannian solutions. in the second part of the paper we look for non - riemannian solutions. we define the notion of a " weyl pseudoinstanton " ( metric compatible spacetime whose curvature is purely weyl ) and prove that a weyl pseudoinstanton is a solution of our field equations. using the pseudoinstanton approach we construct explicitly a non - riemannian solution which is a wave of torsion in minkowski space. we discuss the possibility of using this non - riemannian solution as a mathematical model for the graviton or the neutrino.
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arxiv:gr-qc/0304028
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the excitations in graphene and some other materials are described by two - dimensional massless dirac equation with applied external potential of some kind. solutions of this zero energy equation are built analytically for a wide class of scalar potentials. in contrast to most publications on analytical solutions of massless two - dimensional dirac equation, our potentials really depend on both spatial coordinates in some bounded domain. several examples of such construction are given explicitly.
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arxiv:1811.01637
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we study representations of groups by " affine " automorphisms of compact, convex spaces, with special focus on " irreducible " representations : equivalently " minimal " actions. when the group in question is psl ( 2, r ), we exhibit a one - one correspondence between bounded harmonic functions on the upper half - plane and a certain class of irreducible representations. our analysis shows that, surprisingly, all these representations are equivalent. in fact we find that all irreducible affine representations of this group are equivalent. the key to this is a property we call " linear stone - weierstrass " for group actions on compact spaces, which, if it holds for the " universal strongly proximal space " of the group ( to be defined ) then the induced action on the space of probability measures on this space is the unique irreducible affine representation of the group.
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arxiv:1512.05087
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solar - like oscillations have been observed by { { \ it kepler } } and corot in several solar - type stars. we study the variations of stellar p - mode linewidth as a function of effective temperature. time series of 9 months of kepler data have been used. the power spectra of 42 cool main - sequence stars and subgiants have been analysed using both maximum likelihood estimators and bayesian estimators, providing individual mode characteristics such as frequencies, linewidths and mode heights. here we report on the mode linewidth at maximum power and at maximum mode height for these 42 stars as a function of effective temperature. we show that the mode linewidth at either maximum mode height or maximum amplitude follows a scaling relation with effective temperature, which is a combination of a power law plus a lower bound. the typical power law index is about 13 for the linewidth derived from the maximum mode height, and about 16 for the linewidth derived from the maximum amplitude while the lower bound is about 0. 3 microhz and 0. 7 microhz, respectively. we stress that this scaling relation is only valid for the cool main - sequence stars and subgiants, and does not have predictive power outside the temperature range of these stars.
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arxiv:1112.3295
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the self - energy of the critical 3 - dimensional o ( n ) model is calculated. the analysis is performed in the context of the non - perturbative renormalization group, by exploiting an approximation which takes into account contributions of an infinite number of vertices. a very simple calculation yields the 2 - point function in the whole range of momenta, from the uv gaussian regime to the scaling one. results are in good agreement with best estimates in the literature for any value of n in all momenta regimes. this encourages the use of this simple approximation procedure to calculate correlation functions at finite momenta in other physical situations.
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arxiv:0708.0238
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much of the research and discourse on risks from artificial intelligence ( ai ) image generators, such as dall - e and midjourney, has centered around whether they could be used to inject false information into political discourse. we show that spammers and scammers - seemingly motivated by profit or clout, not ideology - are already using ai - generated images to gain significant traction on facebook. at times, the facebook feed is recommending unlabeled ai - generated images to users who neither follow the pages posting the images nor realize that the images are ai - generated, highlighting the need for improved transparency and provenance standards as ai models proliferate.
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arxiv:2403.12838
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traffic shaping is a mechanism used by internet service providers ( isps ) to limit subscribers ' traffic based on their service contracts. this paper investigates the current implementation of traffic shaping based on the token bucket filter ( tbf ), discusses its advantages and disadvantages, and proposes a cooperative tbf that can improve subscribers ' quality of service ( qos ) / quality of experience ( qoe ) without compromising business aspects of the service contract model by proportionally allocating excess bandwidth from inactive subscribers to active ones based on the long - term bandwidths per their service contracts.
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arxiv:1308.5397
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problem definition : vehicle - to - grid increases the low utilization rate of privately owned electric vehicles by making their batteries available to electricity grids. we formulate a robust optimization problem that maximizes a vehicle owner ' s expected profit from selling primary frequency regulation to the grid and guarantees that market commitments are met at all times for all frequency deviation trajectories in a functional uncertainty set that encodes applicable legislation. faithfully modeling the energy conversion losses during battery charging and discharging renders this optimization problem non - convex. methodology / results : by exploiting a total unimodularity property of the uncertainty set and an exact linear decision rule reformulation, we prove that this non - convex robust optimization problem with functional uncertainties is equivalent to a tractable linear program. through extensive numerical experiments using real - world data, we quantify the economic value of vehicle - to - grid and elucidate the financial incentives of vehicle owners, aggregators, equipment manufacturers, and regulators. managerial implications : we find that the prevailing penalties for non - delivery of promised regulation power are too low to incentivize vehicle owners to honor the delivery guarantees given to grid operators.
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arxiv:2005.06042
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large language models have proven themselves highly flexible, able to solve a wide range of generative tasks, such as abstractive summarization and open - ended question answering. in this paper we extend the capabilities of llms by directly attaching a small audio encoder allowing it to perform speech recognition. by directly prepending a sequence of audial embeddings to the text token embeddings, the llm can be converted to an automatic speech recognition ( asr ) system, and be used in the exact same manner as its textual counterpart. experiments on multilingual librispeech ( mls ) show that incorporating a conformer encoder into the open sourced llama - 7b allows it to outperform monolingual baselines by 18 % and perform multilingual speech recognition despite llama being trained overwhelmingly on english text. furthermore, we perform ablation studies to investigate whether the llm can be completely frozen during training to maintain its original capabilities, scaling up the audio encoder, and increasing the audio encoder striding to generate fewer embeddings. the results from these studies show that multilingual asr is possible even when the llm is frozen or when strides of almost 1 second are used in the audio encoder opening up the possibility for llms to operate on long - form audio.
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arxiv:2307.11795
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the aim of this note is a classification of all nice and all inductively factored reflection arrangements. it turns out that apart from the supersolvable instances only the monomial groups $ g ( r, r, 3 ) $ for $ r \ ge 3 $ give rise to nice reflection arrangements. as a consequence of this and of the classification of all inductively free reflection arrangements from our earlier work, we deduce that the class of all inductively factored reflection arrangements coincides with the supersolvable reflection arrangements. moreover, we extend these classifications to hereditarily factored and hereditarily inductively factored reflection arrangements.
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arxiv:1505.04603
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the main aim of this article is to find all solutions of the diophantine equation $ x ^ 2 + p ^ k = y ^ n $ where $ p \ equiv 1 \ pmod 4 $, $ \ frac { p - 1 } { 3 } $ is a perfect square and the class number of $ \ mathbb { z } [ \ sqrt { - p } ] $ is $ 2 $. in this article, i used a method involving prime factorization and class numbers which is different from using congruent number argument which is widely used in this type of problem.
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arxiv:2402.19445
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in this letter, we analyze the secrecy outage probability ( sop ) over fluctuating two - ray fading channels but with a different definition from the one adopted in [ 5 ]. following the new defined sop, we derive an analytical closed - form expression for our proposed sop, as well as an asymptotic formula valid in the high signal - to - noise ratio region of the source to destination link. in the numerical results section, we perform some monte - carlo simulations to validate the accuracy of our derived expressions, and also present the probability gap between our proposed sop and the sop in [ 5 ].
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arxiv:1905.12396
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recent years have witnessed an exponential growth of the commercial space industry, including rocket launch, satellite network deployment, private space travel, and even extraterrestrial colonization. several trends are predicted in this unprecedented transition to an era of space - enabled broadband access.
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arxiv:2207.00151
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the decays $ \ bar { b } \ to \ bar { k } d $ and $ \ bar { b } \ to \ bar { k } \ bar { d } $ taking into account final state interactions are discussed. these decays are described by four strong phases $ \ delta _ 0, \ delta _ 1, \ tilde { \ delta } _ 0, \ tilde { \ delta } _ 1 $ ( subscript 0 and 1 refer to i = 0 and i = 1 isospin final states ), one weak phase $ \ gamma $ and four real amplitudes. isospin constraints are taken into account. it is argued that strong interaction dynamics gives $ \ delta _ 1 \ approx \ tilde { \ delta } _ 1 $. the four real amplitudes are estimated. some observable consequences are discussed.
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arxiv:hep-ph/0005145
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by considering delta function sextupole, octupole, and decapole perturbations and using difference action - angle variable equations, we find some useful analytical formulae for the estimation of the dynamic apertures of circular accelerators due to single sextupole, single octupole, single decapole ( single 2 $ m $ pole in general ). their combined effects are derived based on the chirikov criterion of the onset of stochastic motions. comparisons with numerical simulations are made, and the agreement is quite satisfactory. these formulae have been applied to determine the beam - beam limited dynamic aperture in a circular collider.
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arxiv:physics/0005023
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spatial correlation between atoms can generate a depletion in the energy dispersion of acoustic phonons. two well known examples are rotons in superfluid helium and the kohn anomaly in metals. here we report on the observation of a large softening of the transverse acoustic mode in quantum paraelectric srtio $ _ 3 $ by means of inelastic neutron scattering. in contrast to other known cases, this softening occurs at a tiny wave vector implying spatial correlation extending over a distance as long as 40 lattice parameters. we attribute this to the formation of mesoscopic fluctuating domains due to the coupling between local strain and quantum ferroelectric fluctuations. thus, a hallmark of the ground state of insulating srtio $ _ 3 $ is the emergence of hybridized optical - acoustic phonons. mesoscopic fluctuating domains play a role in quantum tunneling, which impedes the emergence of a finite macroscopic polarisation.
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arxiv:2203.15495
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modern password hashing remains a critical defense against credential cracking, yet the transition from theoretically secure algorithms to robust real - world implementations remains fraught with challenges. this paper presents a dual analysis of argon2, the password hashing competition winner, combining attack simulations quantifying how parameter configurations impact guessing costs under realistic budgets, with the first large - scale empirical study of argon2 adoption across public github software repositories. our economic model, validated against cryptocurrency mining benchmarks, demonstrates that owasp ' s recommended 46 mib configuration reduces compromise rates by 42. 5 % compared to sha - 256 at \ $ 1 / account attack budgets for strong user passwords. however, memory - hardness exhibits diminishing returns as increasing allocations to rfc 9106 ' s 2048 mib provides just 23. 3 % ( \ $ 1 ) and 17. 7 % ( \ $ 20 ) additional protection despite 44. 5 times greater memory demands. crucially, both configurations fail to mitigate risks from weak passwords, with 96. 9 - 99. 8 % compromise rates for rockyou - like credentials regardless of algorithm choice. our repository analysis shows accelerating argon2 adoption, yet weak configuration practices : 46. 6 % of deployments use weaker - than - owasp parameters. surprisingly, sensitive applications ( password managers, encryption tools ) show no stronger configurations than general software. our findings highlight that a secure algorithm alone cannot ensure security, effective parameter guidance and developer education remain essential for realizing argon2 ' s theoretical advantages.
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arxiv:2504.17121
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understanding human dynamics is of major scientific and practical importance and can be increasingly addressed in a quantitative fashion thanks to electronic records capturing various human activity patterns. the authors of ref. [ 1 ] revisit the datasets studied in ref. [ 2 ], making four technical observations. some of the observations of ref. [ 1 ] are based on the authors ' unfamiliarity with the details of the data collection process and have little relevance to the findings of ref. [ 2 ] and others are resolved in quantitative fashion by other authors [ 3 ].
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arxiv:physics/0511186
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plasma wave observations from voyager 1 have recently shown large increases in plasma density, to about 0. 1 cm ^ { - 3 }, consistent with the density of the local interstellar medium. however, corresponding magnetic field observations continue to show the spiral magnetic field direction observed throughout the inner heliosheath. these apparently contradictory observations may be reconciled if voyager 1 is inside an interstellar flux transfer event - similar to flux transfer events routinely seen at the earth ' s magnetopause. if this were the case, voyager 1 remains inside the heliopause and based on the voyager 1 observations we can determine the polarity of the interstellar magnetic field for the first time.
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arxiv:1309.6546
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in this paper, a compressed sensing ( cs ) based framework of multi - target cooperative visible light positioning ( vlp ) is formulated to realize simultaneous highaccuracy localization of multiple targets. the light emitting diodes ( leds ) intended for illumination are utilized to locate multiple target mobile terminals equipped with photodetectors. the indoor area can be divided into a two - dimensional grid of discrete points, and the targets are located in only a few grid points, which has a sparse property. thus, the multitarget localization problem can be transferred into a sparse recovery problem. specifically, a cs - based framework is formulated exploiting the superposition of the received visible light signals at the multiple targets to be located via intertarget cooperation. then it can be efficiently resolved using cs - based algorithms. moreover, inter - anchor cooperation is introduced to the cs - based framework by the crosscorrelation between the signals corresponding to different leds, i. e., anchors, which further improves the localization accuracy. enabled by the proposed cs - based framework and the devised cooperation mechanism, the proposed scheme can simultaneously locate multiple targets with high precision and low computational complexity. simulation results show that the proposed schemes can achieve centimeter - level multitarget positioning with sub - meter accuracy, which outperforms existing benchmark schemes.
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arxiv:2303.02643
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different approaches to describe compton scattering and the polarizability of the nucleon have been discussed up to now. we show that the most appropriate ones are provided by non - subtracted dispersion theories of the fixed - $ t $ and fixed - $ \ theta $ types, where the properties of these two versions are complementary so that advantage can be taken from both of them. in the frame of fixed - $ t $ dispersion theory it was possible to precisely reproduce experimental differential cross sections obtained for the proton in a wide angular range and for energies up to 1 gev. at energies of the first resonance region and below, precise values for the electromagnetic polarizabilities and spin - polarizabilities have been determined for the proton and the neutron. the data show that diamagnetism is a prominent property of nucleon structure, where the underlying mechanism is a $ t $ - channel $ \ sigma $ - meson exchange. a similar mechanism is responsible for the backward spin - polarizability where the relevant meson is the $ \ pi ^ 0 $. it is a challenge for further research to integrate the $ \ sigma $ and $ \ pi ^ 0 $ intermediate states into a consistent description of the structure of the nucleon.
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arxiv:hep-ph/0501167
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we prove obnservation 2 in arxiv : math / 0402386 by gert almkvist and wadim zudilin.
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arxiv:0907.2597
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the concept of a stare - mode astrometric space mission is introduced. the traditionally accepted mode of operation for a mapping astrometric space mission is that of a continuously scanning satellite, like the successful hipparcos and planned gaia missions. with the advent of astrometry missions mapping out stars to 20th magnitude, the stare - mode becomes competitive. a stare - mode of operation has several advantages over a scanning missions if absolute parallax and throughput issues can be successfully addressed. requirements for a stare - mode operation are outlined. the mission precision for a stare - mode astrometric mission is derived as a function of instrumental parameters with examples given. the stare - mode concept has been accepted as baseline for the nasa roadmap study of the origins billions star survey ( obss ) mission and the milli - arcsecond pathfinder survey ( maps ) micro - satellite proposed project.
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arxiv:astro-ph/0608286
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sleptons, neutralinos and charginos were searched for in the context of scenarios where the lightest supersymmetric particle is the gravitino. it was assumed that the stau is the next - to - lightest supersymmetric particle. data collected with the delphi detector at a centre - of - mass energy near 189 gev were analysed combining the methods developed in previous searches at lower energies. no evidence for the production of these supersymmetric particles was found. hence, limits were derived at 95 % confidence level.
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arxiv:hep-ex/0103026
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in human - ai interaction, a prominent goal is to attain human ` s desirable outcome with the assistance of ai agents, which can be ideally delineated as a problem of seeking the optimal nash equilibrium that matches the human ` s desirable outcome. however, reaching the outcome is usually challenging due to the existence of multiple nash equilibria that are related to the assisting task but do not correspond to the human ` s desirable outcome. to tackle this issue, we employ a theoretical framework called structural causal game ( scg ) to formalize the human - ai interactive process. furthermore, we introduce a strategy referred to as pre - policy intervention on the scg to steer ai agents towards attaining the human ` s desirable outcome. in more detail, a pre - policy is learned as a generalized intervention to guide the agents ` policy selection, under a transparent and interpretable procedure determined by the scg. to make the framework practical, we propose a reinforcement learning - like algorithm to search out this pre - policy. the proposed algorithm is tested in both gridworld environments and realistic dialogue scenarios with large language models, demonstrating its adaptability in a broader class of problems and potential effectiveness in real - world situations.
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arxiv:2405.16588
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we introduce a semiclassical theory for strong localization that may arise in the context of many - body thermalization. as a minimal model for thermalization we consider a few - site bose - hubbard model consisting of two weakly interacting subsystems that can exchange particles. the occupation of a subsystem ( $ x $ ) satisfies in the classical treatment a fokker - planck equation with a diffusion coefficient $ d ( x ) $. we demonstrate that it is possible to deduce from the classical description a quantum breaktime $ t ^ * $, and hence the manifestations of a strong localization effect. for this purpose it is essential to take the geometry of the energy shell into account, and to make a distinction between different notions of phasespace exploration.
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arxiv:1711.01740
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we present an approach for constructing a surrogate from ensembles of information sources of varying cost and accuracy. the multifidelity surrogate encodes connections between information sources as a directed acyclic graph, and is trained via gradient - based minimization of a nonlinear least squares objective. while the vast majority of state - of - the - art assumes hierarchical connections between information sources, our approach works with flexibly structured information sources that may not admit a strict hierarchy. the formulation has two advantages : ( 1 ) increased data efficiency due to parsimonious multifidelity networks that can be tailored to the application ; and ( 2 ) no constraints on the training data - - we can combine noisy, non - nested evaluations of the information sources. numerical examples ranging from synthetic to physics - based computational mechanics simulations indicate the error in our approach can be orders - of - magnitude smaller, particularly in the low - data regime, than single - fidelity and hierarchical multifidelity approaches.
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arxiv:2008.02672
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extreme mass ratio inspirals ( emris ) can be classified as dry emris and wet emris based on their formation mechanisms. dry ( or the " loss - cone " ) emris, previously considered as the main emri sources for the laser interferometer space antenna, are primarily produced by multi - body scattering in the nuclear star cluster and gravitational capture. in this work, we highlight an alternative emri formation channel : ( wet ) emri formation assisted by the accretion flow around accreting galactic - center massive black holes ( mbhs ). in this channel, the accretion disk captures stellar - mass black holes that are intially moving on inclined orbits, and subsequently drives them to migrate towards the mbh - this process boosts the formation rate of emris in such galaxies by orders of magnitude. taking into account the fraction ( $ \ mathcal o ( 10 ^ { - 2 } - 10 ^ { - 1 } ) $ ) of active galactic nuclei where the mbhs are expected to be rapidly accreting, we forecast that wet emris will contribute an important or even dominant fraction of all detectable emris by spaceborne gravitational wave detectors.
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arxiv:2104.01208
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in this scientific article, the data on air pollution by pm2. 5 particulate matter was evaluated in different locations in the city of cusco with respect to the environmental quality indexes ( inca ) of the ministry of the environment of the peruvian government. the results show that air pollution in the city of cusco is an environmental risk problem. more than 84 % of the monitored sites have a bad rating ( 101 - 500 ), the corresponding color is orange. this result shows that the air that citizens of cusco breathe is of poor quality and the population could experience health problems. the recommendation is to avoid outdoor exercises and activities. in the district of san jeronimo cusco, the average concentration has been 125 ug / m3, which corresponds to the inca interval of more than 125, within the red color threshold for care. the health effects are described as chronic lung and cardiovascular diseases, and the health authority should declare levels of alert. it has been concluded that according to inca, the air in the city of cusco is of poor quality and falls within the threshold of the care state value ( vuec ).
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arxiv:2305.15414
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the pooled data problem asks to identify the unknown labels of a set of items from condensed measurements. more precisely, given $ n $ items, assume that each item has a label in $ \ cbc { 0, 1, \ ldots, d } $, encoded via the ground - truth $ \ sigma $. we call the pooled data problem sparse if the number of non - zero entries of $ \ sigma $ scales as $ k \ sim n ^ { \ theta } $ for $ \ theta \ in ( 0, 1 ) $. the information that is revealed about $ \ sigma $ comes from pooled measurements, each indicating how many items of each label are contained in the pool. the most basic question is to design a pooling scheme that uses as few pools as possible, while reconstructing $ \ sigma $ with high probability. variants of the problem and its combinatorial ramifications have been studied for at least 35 years. however, the study of the modern question of \ emph { efficient } inference of the labels has suggested a statistical - to - computational gap of order $ \ log n $ in the minimum number of pools needed for theoretically possible versus efficient inference. in this article, we resolve the question whether this $ \ log n $ - gap is artificial or of a fundamental nature by the design of an efficient algorithm, called \ algoname, based upon a novel pooling scheme on a number of pools very close to the information - theoretic threshold.
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arxiv:2312.14588
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classical tests of fit typically reject a model for large enough real data samples. in contrast, often in statistical practice a model offers a good description of the data even though it is not the " true " random generator. we consider a more flexible approach based on contamination neighbourhoods around a model. using trimming methods and the kolmogorov metric we introduce a functional statistic measuring departures from a contaminated model and the associated estimator corresponding to its sample version. we show how this estimator allows testing of fit for the ( slightly ) contaminated model vs sensible deviations from it, with uniformly exponentially small type i and type ii error probabilities. we also address the asymptotic behavior of the estimator showing that, under suitable regularity conditions, it asymptotically behaves as the supremum of a gaussian process. as an application we explore methods of comparison between descriptive models based on the paradigm of model falseness. we also include some connections of our approach with the false - discovery - rate setting, showing competitive behavior when estimating the contamination level, although applicable in a wider framework.
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arxiv:1903.08687
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we present a novel dataset that extends our view of the cosmic gas around z $ \ approx $ 3 - 4 ly $ \ alpha $ emitting galaxies ( laes ) in the muse analysis of gas around galaxies ( magg ) survey by tracing a cool and enriched gas phase through 47 mgii absorbers identified in newly - obtained vlt / xshooter near - infrared quasar spectra. jointly with the more ionized gas traced by civ systems and the neutral hi from previous work, we find that laes are distributed inside cosmic structures that contain multiphase gas in composition and temperature. all gas phases are a strong function of the large - scale galaxy environment : the mgii and the civ strength and kinematics positively correlate with the number of associated galaxies, and it is $ \ approx $ 3 - 4 times more likely to detect metal absorbers around group than isolated laes. exploring the redshift evolution, the covering factor of mgii around group and isolated laes remains approximately constant from z $ \ approx $ 3 - 4 to z < 2, but the one of civ around group galaxies drops by z < 2. adding the cool enriched gas traced by the mgii absorbers to the results we obtained for the hi and civ gas, we put forward a picture in which laes lie along gas filaments that contain high column - density hi systems and are enriched by strong civ and mgii absorbers. while the mgii gas appears to be more centrally concentrated near laes, weaker civ systems trace instead a more diffuse gas phase extended up to larger distances around the galaxies.
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arxiv:2406.10350
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primordial gravitational waves are expected to create a stochastic background encoding information about the early universe that may not be accessible by other means. however, the primordial background is obscured by an astrophysical foreground consisting of gravitational waves from compact binaries. we demonstrate a bayesian method for estimating the primordial background in the presence of an astrophysical foreground. since the background and foreground signal parameters are estimated simultaneously, there is no subtraction step, and therefore we avoid astrophysical contamination of the primordial measurement, sometimes referred to as " residuals ". additionally, since we include the non - gaussianity of the astrophysical foreground in our model, this method represents the statistically optimal approach to the simultaneous detection of a multi - component stochastic background.
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arxiv:2009.04418
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we recently reported that the simple genetic algorithm ( sga ) is capable of performing a remarkable form of sublinear computation which has a straightforward connection with the general problem of interacting attributes in data - mining. in this paper we explain how the sga can leverage this computational proficiency to perform efficient adaptation on a broad class of fitness functions. based on the relative ease with which a practical fitness function might belong to this broad class, we submit a new hypothesis about the workings of genetic algorithms. we explain why our hypothesis is superior to the building block hypothesis, and, by way of empirical validation, we present the results of an experiment in which the use of a simple mechanism called clamping dramatically improved the performance of an sga with uniform crossover on large, randomly generated instances of the max 3 - sat problem.
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arxiv:0905.2473
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dense matrix multiplication ( matmul ) is arguably one of the most ubiquitous compute - intensive kernels, spanning linear algebra, dsp, graphics, and machine learning applications. thus, matmul optimization is crucial not only in high - performance processors but also in embedded low - power platforms. several instruction set architectures ( isas ) have recently included matrix extensions to improve matmul performance and efficiency at the cost of added matrix register files and units. in this paper, we propose matrix extension ( mx ), a lightweight approach that builds upon the open - source risc - v vector ( rvv ) isa to boost matmul energy efficiency. instead of adding expensive dedicated hardware, mx uses the pre - existing vector register file and functional units to create a hybrid vector / matrix engine at a negligible area cost ( < 3 % ), which comes from a compact near - fpu tile buffer for higher data reuse, and no clock frequency overhead. we implement mx on a compact and highly energy - optimized rvv processor and evaluate it in both a dual - and 64 - core cluster in a 12 - nm technology node. mx boosts the dual - core ' s energy efficiency by 10 % for a double - precision 64x64x64 matrix multiplication with the same fpu utilization ( ~ 97 % ) and by 25 % on the 64 - core cluster for the same benchmark on 32 - bit data, with a 56 % performance gain.
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arxiv:2401.04012
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in 2003, fomin and zelevinsky proved that finite type cluster algebras can be classified by dynkin diagrams. then in 2013, barot and marsh defined the presentation of a reflection group associated to a dynkin diagram in terms of an edge - weighted, oriented graph, and proved that this group is invariant ( up to isomorphism ) under diagram mutations. in this paper, we extend barot and marsh ' s results to artin group presentations, defining new generator relations and showing mutation - invariance for these presentations.
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arxiv:1410.3530
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we lay down the foundation of the theory of spaces of distributions on the product $ x _ 1 \ times x _ 2 $ of doubling metric measure spaces $ x _ 1 $, $ x _ 2 $ in the presence of non - negative self - adjoint operators $ l _ 1 $, $ l _ 2 $, whose heat kernels have gaussian localization and the markov property. this theory includes the development of two - parameter functional calculus induced by $ l _ 1, l _ 2 $, integral operators with highly localized kernels, test functions and distributions associated to $ l _ 1, l _ 2 $, spectral spaces accompanied by maximal peetre and nikolski type inequalities. hardy spaces are developed in this two - parameter product setup. two types of besov and triebel - lizorkin spaces are introduced and studied : ordinary spaces and spaces with dominating mixed smoothness, with emphasis on the latter. embedding results are obtained and spectral multiplies are developed.
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arxiv:2312.16718
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purpose : the study aimed to improve the previous study covering a web - based query game for cavite state university. the study created a new mechanic and gameplay for the students to learn structured query language ( sql ). the enhancements also focused on the interactions of one or more students playing the game. method : the researchers used iterative development process methodology in the development of the study. the system was assessed and evaluated using different testing methods : unit, integration, and system testing. after passing the tests, 90 students of information technology and computer science program along with 10 it experts evaluated the system. results : the respondents were classified into technical and non - technical respondents and the study garnered an evaluation score of 4. 69 and 4. 70 respectively. the overall interpretation of the results of the evaluation is excellent. conclusion : the study created a system where the user can read and watch lectures and experience the tutorial. instructors and students may communicate in the system, hence, promoting better relations and healthy competition between students. recommendations : based on the conclusions of the study, the system can be used as a supplementary tool in teaching courses with database management. to enhance the analysis of query construction of the students, it is recommended to add a module that can analyze the pattern of creating queries and answering questions for every user.
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arxiv:2012.02237
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as a mysterious celestial body predicted by general relativity, black holes have been confirmed by observations in recent years. but there are still many unknown properties waiting for us to discover, one of the famous problems is the quantization of black holes. the quantization of black holes gives new research significance to black holes, but the quantization of black holes is difficult to prove. here we propose a new method to verify the quantization of black holes : carnot cycle. our results show that if the black holes have quantized energy levels, the work w they impose to us via the carnot cycle should also be quantized. we indirectly verify the quantization of black holes by detecting the quantization of w, and contrast it with the classic carnot cycle. in addition, we have also verified the correctness of the second law of thermodynamics under the premise of considering the quantization of black holes.
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arxiv:2202.09038
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regarded as the summit of all knowledge. it became an essential part of european medieval culture. soon after the invention of typography it appeared many times in print. " however, " the scholastics – later medieval philosophers, theologians, and scientists – were helped by the arabic translators and commentaries, but they hardly needed to struggle against a flat - earth legacy from the early middle ages ( 500 – 1050 ). early medieval writers often had fuzzy and imprecise impressions of both ptolemy and aristotle and relied more on pliny, but they felt ( with one exception ), little urge to assume flatness. " st vergilius of salzburg ( c. 700 – 784 ), in the middle of the 8th century, discussed or taught some geographical or cosmographical ideas that st boniface found sufficiently objectionable that he complained about them to pope zachary. the only surviving record of the incident is contained in zachary ' s reply, dated 748, where he wrote : as for the perverse and sinful doctrine which he ( virgil ) against god and his own soul has uttered – if it shall be clearly established that he professes belief in another world and other men existing beneath the earth, or in ( another ) sun and moon there, thou art to hold a council, deprive him of his sacerdotal rank, and expel him from the church. some authorities have suggested that the sphericity of the earth was among the aspects of vergilius ' s teachings that boniface and zachary considered objectionable. others have considered this unlikely, and take the wording of zachary ' s response to indicate at most an objection to belief in the existence of humans living in the antipodes. in any case, there is no record of any further action having been taken against vergilius. he was later appointed bishop of salzburg and was canonised in the 13th century. a possible non - literary but graphic indication that people in the middle ages believed that the earth ( or perhaps the world ) was a sphere is the use of the orb ( globus cruciger ) in the regalia of many kingdoms and of the holy roman empire. it is attested from the time of the christian late - roman emperor theodosius ii ( 423 ) throughout the middle ages ; the reichsapfel was used in 1191 at the coronation of emperor henry vi. however the word orbis means " circle ", and there is no record of a globe as a representation of the earth since ancient
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https://en.wikipedia.org/wiki/Flat_Earth
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the ligo control and data system ( cds ) features a tightly coupled and highly integrated control and data acquisition system. control of the interferometers requires many multiple input multiple output ( mimo ) control loops closed both locally and across the 4 - kilometer interferometer arm lengths. in addition to providing the closed loop control, the control systems front end processors act as data collection units ( dcu ) for the data acquisition system. data collected by these front ends and the data acquisition system must be collected and time stamped to an accuracy of 1 microsecond and made available to on - line analysis tools such as the global diagnostics system ( gds ) [ 1 ]. data is also sent to the ligo data analysis system ( ldas ) [ 2 ] for long - term storage and off - line analysis. data rates exceed 5 mbytes per second per interferometer continuous. connection between the various front end processors and the data acquisition system is achieved using fiber optic reflective memory networks. both controls and data acquisition systems use vme hardware and vxworks operating systems. this paper will present an overview of the ligo cds and discuss key aspects of its design.
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arxiv:physics/0111077
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we consider cosmological parameters estimation in the presence of a non - zero isocurvature contribution in the primordial perturbations. a previous analysis showed that even a tiny amount of isocurvature perturbation, if not accounted for, could affect standard rulers calibration from cosmic microwave background observations such as those provided by the planck mission, affect baryon acoustic oscillations interpretation and introduce biases in the recovered dark energy properties that are larger than forecasted statistical errors from future surveys. extending on this work, here we adopt a general fiducial cosmology which includes a varying dark energy equation of state parameter and curvature. beside baryon acoustic oscillations measurements, we include the information from the shape of the galaxy power spectrum and consider a joint analysis of a planck - like cosmic microwave background probe and a future, space - based, large scale structure probe not too dissimilar from recently proposed surveys. we find that this allows one to break the degeneracies that affect the cosmic microwave background and baryon acoustic oscillations combination. as a result, most of the cosmological parameter systematic biases arising from an incorrect assumption on the isocurvature fraction parameter $ f _ { iso } $, become negligible with respect to the statistical errors. we find that the cosmic microwave background and large scale structure combination gives a statistical error $ \ sigma ( f _ { iso } ) \ sim 0. 008 $, even when curvature and a varying dark energy equation of state are included, which is smaller than the error obtained from cosmic microwave background alone when flatness and cosmological constant are assumed. these results confirm the synergy and complementarity between cosmic microwave background and large scale structure, and the great potential of future and planned galaxy surveys.
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arxiv:1107.1211
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we consider a homogenization problem for magnetic ginzburg - landau functional in domains with large number of small holes. for sufficiently strong magnetic field, a large number of vortices is formed and they are pinned by the holes. we establish a scaling relation between sizes of holes and the magnitude of the external magnetic field when pinned vortices are multiple and their homogenized density is described by a hierarchy of variational problems. this stands in sharp contrast with homogeneous superconductors, where all vortices are known to be simple. the proof is based on $ \ gamma $ - convergence approach which is applied to a coupled continuum / discrete variational problem : continuum in the induced magnetic field and discrete in the unknown finite ( quantized ) values of multiplicity of vortices pinned by holes.
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arxiv:1105.4369
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we study a geometrically frustrated triangular ising antiferromagnet in an external magnetic field which is selectively diluted with nonmagnetic impurities employing an effective - field theory with correlations and monte carlo simulations. we focus on the frustration - relieving effects of such a selective dilution on the phase diagram and find that it can lead to rather intricate phase diagrams in the dilution - field parameters space. in particular, in a highly ( weakly ) diluted system the frustration is greatly ( little ) relieved and such a system is found to display only the second ( first ) - order phase transitions at any field. on the other hand, for a wide interval of intermediate dilution values the transition remains second order at low fields but it changes to first order at higher fields and the system displays a tricritical behavior. the existence of the first - order transition in the region of intermediate dilution and high fields is verified by monte carlo simulations.
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arxiv:1212.5451
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using elastic and inelastic neutron scattering we show that a cubic spinel, cdcr $ _ 2 $ o $ _ 4 $, undergoes an elongation along the c - axis ( $ c > a = b $ ) at its spin - peierls - like phase transition at $ t _ n $ = 7. 8 k. the n \ ' { e } el phase ( $ t < t _ n $ ) has an incommesurate spin structure with a characteristic wave vector \ textbf { q } $ _ m $ = ( 0, $ \ delta $, 1 ) with $ \ delta \ sim $ 0. 09 and with spins lying on the $ ac $ - plane. this is in stark contrast to another well - known cr - based spinel, zncr $ _ 2 $ o $ _ 4 $, that undergoes a c - axis contraction and a commensurate spin order. the magnetic excitations of the incommensurate n \ ' { e } el state has a weak anisotropy gap of 0. 6 mev and it consists of at least three bands extending up to 5 mev.
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arxiv:cond-mat/0510363
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one way to show that thompson ' s group f is non - amenable is to exhibit an action of f on a locally compact cat ( 0 ) space x containing no f - invariant flats and having no global fixed points in its boundary - at - infinity. we study the actions of thompson ' s groups f, t, and v on the boundaries - at - infinity of proper cat ( 0 ) cubical complexes. in particular, we show that thompson ' s groups t and v act without fixing any points in the boundaries of their cat ( 0 ) cubical complexes. this in particular gives another proof of the well - known fact that these groups are non - amenable. we obtain a partial description of the fixed set for f : thompson ' s group f fixes an arc in the boundary of its cubical complex. we leave open the possibility that there are more fixed points, but describe a region of the boundary which must contain all of the others.
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arxiv:math/0604077
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this paper aims to explore the mechanical effect of a company ' s share repurchase on earnings per share ( eps ). in particular, while a share repurchase scheme will reduce the overall number of shares, suggesting that the eps may increase, clearly the expenditure will reduce the net earnings of a company, introducing a trade - off between these competing effects. we first of all review accretive share repurchases, then characterise the increase in eps as a function of price paid by the company. subsequently, we analyse and quantify the estimated difference in earnings growth between a company ' s natural growth in the absence of buyback scheme to that with its earnings altered as a result of the buybacks. we conclude with an examination of the effect of share repurchases in two cases studies in the us stock - market.
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arxiv:1911.04199
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in this paper we will show how to construct holomorphic l ^ { p } - functions on unbranched coverings of strongly pseudoconvex manifolds. also, we prove some extension and approximation theorems for such functions.
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arxiv:0712.4302
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in these notes we review the calculation of jones polynomials using a matrix representation of the braid group and temperley - lieb algebra. the pseudounitary representation that we consider allows constructing ` ` states ' ' from the group / algebra matrices and compute the knot invariants as matrix elements, rather than traces. in comparison with a more standard way of computing the invariants through traces, the matrix element method is more interesting and complete from the point of view of applications. as a byproduct of the discussion we prove a general formula for pretzel knots.
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arxiv:2403.17227
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let $ \ omega \ subset \ mathbb { r } ^ 3 $ be a domain and let $ f \ in bv _ { \ operatorname { loc } } ( \ omega, \ mathbb { r } ^ 3 ) $ be a homeomorphism such that its distributional adjugate is a finite radon measure. we show that its inverse has bounded variation $ f ^ { - 1 } \ in bv _ { \ operatorname { loc } } $. the condition that the distributional adjugate is finite measure is not only sufficient but also necessary for the weak regularity of the inverse.
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arxiv:1804.03449
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we consider exact deterministic mixed - integer programming ( mip ) reformulations of distributionally robust chance - constrained programs ( dr - ccp ) with random right - hand sides over wasserstein ambiguity sets. the existing mip formulations are known to have weak continuous relaxation bounds, and, consequently, for hard instances with small radius, or with large problem sizes, the branch - and - bound based solution processes suffer from large optimality gaps even after hours of computation time. this significantly hinders the practical application of the dr - ccp paradigm. motivated by these challenges, we conduct a polyhedral study to strengthen these formulations. we reveal several hidden connections between dr - ccp and its nominal counterpart ( the sample average approximation ), mixing sets, and robust 0 - 1 programming. by exploiting these connections in combination, we provide an improved formulation and two classes of valid inequalities for dr - ccp. we test the impact of our results on a stochastic transportation problem numerically. our experiments demonstrate the effectiveness of our approach ; in particular our improved formulation and proposed valid inequalities reduce the overall solution times remarkably. moreover, this allows us to significantly scale up the problem sizes that can be handled in such dr - ccp formulations by reducing the solution times from hours to seconds.
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arxiv:2003.12685
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a bose star passing through cold molecular clouds may capture atoms, molecules and dust particles. the observational signature of such an event would be a relatively small amount of matter that is gravitationally bound. this binding may actually be provided by invisible dark matter forming the bose star. we may expect a relative excess of heavier atoms, molecules, and solid dust compared to the content of giant cold molecular clouds since the velocity of heavy particles at a given temperature is lower and it may be small compared to the escape velocity, $ v _ \ mathrm { rms } = \ sqrt { 3k _ \ mathrm { b } t / m _ \ mathrm { gas } } \ ll v _ \ mathrm { esc } = \ sqrt { 2gm / r } $. finally, the velocity of this captured matter cloud may correlate with the expected velocity of free dark matter particles ( e. g. expected axion wind velocity relative to earth ).
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arxiv:2407.21262
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we establish the uniqueness of semi - wavefront solution for a non - local delayed reaction - diffusion equation. this result is obtained by using a generalization of the diekman - kaper theory for a nonlinear convolution equation. several applications to the systems of non - local reaction - diffusion equations with distributed time delay are also considered.
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arxiv:1309.4376
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the energy associated with bosonic and fermionic pairs of topological spin defects in doped antiferromagnetic quantum spin - 1 / 2 square lattice is estimated within a resonating valence bond scenario, as described by a t - t ' - j - like model hamiltonian, plus a t - perpendicular, responsible of a three - dimensional screening of the electrostatic repulsion within the bosonic pairs. for parameters appropriate for monolayered high - t _ c superconductors, both fermionic and bosonic pairs show x ^ 2 - y ^ 2 symmetry. we find a critical value of doping such that the energy of the bosonic pairs goes below twice the energy of two fermionic pairs at their fermi level. this finding could be related to the onset of high - t _ c superconductivity.
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arxiv:cond-mat/0507452
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this essay discusses some geometric effects associated with gravitomagnetic fields and gravitomagnetic charge as well as the gravity theory of the latter. gravitomagnetic charge is the duality of gravitoelectric charge ( mass ) and is therefore also termed the dual mass which represents the topological property of gravitation. the field equation of gravitomagnetic matter is suggested and a static spherically symmetric solution of this equation is offered. a possible explanation of the anomalous acceleration acting on pioneer spacecrafts are briefly proposed.
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arxiv:gr-qc/0301067
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we study the properties of discrete - time random walks on networks formed by randomly interconnected cliques, namely, random networks of cliques. our purpose is to derive the parameters that define the network structure - - specifically, the distribution of clique size and the abundance of inter - clique links - - from the observation of selected statistical features along the random walk. to this end, we apply a bayesian approach based on recording the times spent by the walker inside successively visited cliques. the procedure is illustrated with some numerical examples of diverse complexity, where the relevant structural parameters are successfully recovered.
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arxiv:2504.16717
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we completely describe the components of expected dimension of the hilbert scheme of rational curves of fixed degree $ k $ in the moduli space $ { \ rm su } _ { c } ( r, l ) $ of semistable vector bundles of rank $ r $ and determinant $ l $ on a curve $ c $. we show that for every $ k \ geq 1 $ there are $ { \ rm gcd } ( r, \ deg l ) $ unobstructed components. in addition, if $ k $ is divisible by $ r _ 1 ( r - r _ 1 ) ( g - 1 ) $ for $ 1 \ le r _ 1 \ le r - 1 $, there is an additional obstructed component of the expected dimension for each such $ r _ 1 $. we construct families of obstructed components and show that their generic point is not the generic vector bundle of given rank and determinant. finally, we also obtain an upper bound on the degree of rational connectedness of $ { \ rm su } _ { c } ( r, l ) $ which is linear in the dimension.
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arxiv:2007.10511
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we partially generalize the results of kudla and rallis on the poles of degenerate, siegel - parabolic eisenstein series to residual - data eisenstein series. in particular, for $ a, b $ integers greater than 1, we show that poles of the eisenstein series induced from the speh representation $ \ delta ( \ tau, b ) $ on the levi $ \ mathrm { gl } _ { ab } $ of $ \ mathrm { sp } _ { 2ab } $ are located in the " segment " of half integers $ x _ { b } $ between a " right endpoint " and its negative, inclusive of endpoints. the right endpoint is $ \ pm b / 2 $, or $ ( b - 1 ) / 2 $, depending on the analytic properties of the automorphic $ l $ - functions attached to $ \ tau $. we study the automorphic forms $ \ phi _ { i } ^ { ( b ) } $ obtained as residues at the points $ s _ i ^ { ( b ) } $ ( defined precisely in the paper ) by calculating their cuspidal exponents in certain cases. in the case of the " endpoint " $ s _ 0 ^ { ( b ) } $ and ` first interior point ' $ s _ 1 ^ { ( b ) } $ in the segment of singularity points, we are able to determine a set containing \ textit { all possible } cuspidal exponents of $ \ phi _ 0 ^ { ( b ) } $ and $ \ phi _ 1 ^ { ( b ) } $ precisely for all $ a $ and $ b $. in these cases, we use the result of the calculation to deduce that the residual automorphic forms lie in $ l ^ 2 ( g ( k ) \ backslash g ( \ mathbf { a } ) ) $. in a more precise sense, our result establishes a relationship between, on the one hand, the actually occurring cuspidal exponents of $ \ phi _ i ^ { ( b ) } $, residues at interior points which lie to the right of the origin, and, on the other hand, the " analytic properties " of the original residual - data eisenstein series at the origin. this preprint is a longer version of the paper " analytic properties of residual eisenstein series, i ", with the details of some proofs added and some additional examples adduced
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arxiv:0908.3667
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hexagonal boron nitride ( hbn ) has been experimentally shown to exhibit room - temperature single - photon emission. this emission is attributed to defect states in the wide band - gap of hbn, which allow new optical transitions between these dispersion - less defect levels. in this work, we study the new spectral features introduced by interacting atomic defects in consecutive layers of bilayer hbn. density functional theory simulations have been carried out to calculate the energy band structure, frequency - dependent complex dielectric functions, and kohn - sham states to demonstrate and understand the cause of the emission enhancements. we found that placing colour centres in the vicinity of each other in bilayer hbn introduces new polarization dependent spectral features, with strong dependence on the distance and relative orientation between atomic defects. our results provide a pathway to engineering single photon emission in hbn via inter - defect interaction.
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arxiv:2411.09346
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the building of planetary systems is controlled by the gas and dust dynamics of protoplanetary disks. while the gas is simultaneously accreted onto the central star and dissipated away by winds, dust grains aggregate and collapse to form planetesimals and eventually planets. this dust and gas dynamics involves instabilities, turbulence and complex non - linear interactions which ultimately control the observational appearance and the secular evolution of these disks. this chapter is dedicated to the most recent developments in our understanding of the dynamics of gaseous and dusty disks, covering hydrodynamic and magnetohydrodynamic turbulence, gas - dust instabilities, dust clumping and disk winds. we show how these physical processes have been tested from observations and highlight standing questions that should be addressed in the future.
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arxiv:2203.09821
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accurately modeling user preferences is vital not only for improving recommendation performance but also for enhancing transparency in recommender systems. conventional user profiling methods, such as averaging item embeddings, often overlook the evolving, nuanced nature of user interests, particularly the interplay between short - term and long - term preferences. in this work, we leverage large language models ( llms ) to generate natural language summaries of users ' interaction histories, distinguishing recent behaviors from more persistent tendencies. our framework not only models temporal user preferences but also produces natural language profiles that can be used to explain recommendations in an interpretable manner. these textual profiles are encoded via a pre - trained model, and an attention mechanism dynamically fuses the short - term and long - term embeddings into a comprehensive user representation. beyond boosting recommendation accuracy over multiple baselines, our approach naturally supports explainability : the interpretable text summaries and attention weights can be exposed to end users, offering insights into why specific items are suggested. experiments on real - world datasets underscore both the performance gains and the promise of generating clearer, more transparent justifications for content - based recommendations.
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arxiv:2505.00886
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social media, as a means for computer - mediated communication, has been extensively used to study the sentiment expressed by users around events or topics. there is however a gap in the longitudinal study of how sentiment evolved in social media over the years. to fill this gap, we develop tm - senti, a new large - scale, distantly supervised twitter sentiment dataset with over 184 million tweets and covering a time period of over seven years. we describe and assess our methodology to put together a large - scale, emoticon - and emoji - based labelled sentiment analysis dataset, along with an analysis of the resulting dataset. our analysis highlights interesting temporal changes, among others in the increasing use of emojis over emoticons. we publicly release the dataset for further research in tasks including sentiment analysis and text classification of tweets. the dataset can be fully rehydrated including tweet metadata and without missing tweets thanks to the archive of tweets publicly available on the internet archive, which the dataset is based on.
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arxiv:2108.13898
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the intrinsic stacking fault energy ( isfe ) $ \ gamma $ is a material parameter fundamental to the discussion of plastic deformation mechanisms in metals. here, we scrutinize the temperature dependence of the isfe of au through accurate first - principles derived helmholtz free energies employing both the super cell approach and the axial ising model ( aim ). a significant decrease of the isfe with temperature, $ - ( 36 $ - $ 39 ) $ \, \ % from 0 to 890 \, k depending on the treatment of thermal expansion, is revealed, which matches the estimate based on the experimental temperature coefficient $ d \ gamma / d t $ closely. we make evident that this decrease predominantly originates from the excess vibrational entropy at the stacking fault layer, although the contribution arising from the static lattice expansion compensates it by approximately 60 \, \ %. electronic excitations are found to be of minor importance for the isfe change with temperature. we show that the debye model in combination with the aim captures the correct sign but significantly underestimates the magnitude of the vibrational contribution to $ \ gamma ( t ) $. the hexagonal close - packed ( hcp ) and double hcp structures are established as metastable phases of au. our results demonstrate that quantitative agreement with experiments can be obtained if all relevant temperature - induced excitations are considered in first - principles modeling and that the temperature dependence of the isfe is substantial enough to be taken into account in crystal plasticity modeling.
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arxiv:1704.00313
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segmentation of head and neck ( h \ & n ) tumours and prediction of patient outcome are crucial for patient ' s disease diagnosis and treatment monitoring. current developments of robust deep learning models are hindered by the lack of large multi - centre, multi - modal data with quality annotations. the miccai 2021 head and neck tumor ( hecktor ) segmentation and outcome prediction challenge creates a platform for comparing segmentation methods of the primary gross target volume on fluoro - deoxyglucose ( fdg ) - pet and computed tomography images and prediction of progression - free survival in h \ & n oropharyngeal cancer. for the segmentation task, we proposed a new network based on an encoder - decoder architecture with full inter - and intra - skip connections to take advantage of low - level and high - level semantics at full scales. additionally, we used conditional random fields as a post - processing step to refine the predicted segmentation maps. we trained multiple neural networks for tumor volume segmentation, and these segmentations were ensembled achieving an average dice similarity coefficient of 0. 75 in cross - validation, and 0. 76 on the challenge testing data set. for prediction of patient progression free survival task, we propose a cox proportional hazard regression combining clinical, radiomic, and deep learning features. our survival prediction model achieved a concordance index of 0. 82 in cross - validation, and 0. 62 on the challenge testing data set.
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arxiv:2111.03848
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in analogy to chapter 9 of arxiv : 0709. 3705 we define an intersection product of tropical cycles on tropical linear spaces l ^ n _ k, i. e. on tropical fans of the type max { 0, x _ 1,..., x _ n } ^ ( n - k ) * r ^ n. afterwards we use this result to obtain an intersection product of cycles on every smooth tropical variety, i. e. on every tropical variety that arises from gluing such tropical linear spaces. in contrast to classical algebraic geometry these products always yield well - defined cycles, not cycle classes only. using these intersection products we are able to define the pull - back of a tropical cycle along a morphism between smooth tropical varieties. in the present article we stick to the definitions, notions and concepts introduced in arxiv : 0709. 3705.
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arxiv:0904.2693
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dynamical universality classes are distinguished by their dynamical exponent $ z $ and unique scaling functions encoding space - time asymmetry for, e. g. slow - relaxation modes or the distribution of time - integrated currents. so far the universality class of the nagel - schreckenberg ( nasch ) model, which is a paradigmatic model for traffic flow on highways, was not known except for the special case $ v _ { \ text { max } } = 1 $. here the model corresponds to the tasep ( totally asymmetric simple exclusion process ) that is known to belong to the superdiffusive kardar - parisi - zhang ( kpz ) class with $ z = 3 / 2 $. in this paper, we show that the nasch model also belongs to the kpz class \ cite { kpz } for general maximum velocities $ v _ { \ text { max } } > 1 $. using nonlinear fluctuating hydrodynamics theory we calculate the nonuniversal coefficients, fixing the exact asymptotic solutions for the dynamical structure function and the distribution of time - integrated currents. performing large - scale monte - carlo simulations we show that the simulation results match the exact asymptotic kpz solutions without any fitting parameter left. additionally, we find that nonuniversal early - time effects or the choice of initial conditions might have a strong impact on the numerical determination of the dynamical exponent and therefore lead to inconclusive results. we also show that the universality class is not changed by extending the model to a two - lane nasch model with dynamical lane changing rules.
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arxiv:1907.00636
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altermagnetism has been proposed as a new type of magnetism, simultaneously exhibiting compensated spin moments in real space and spin - split electronic bands in reciprocal space. alternating chiral magnon splitting is considered a unique feature of altermagnets. in this work, utilizing linear spin wave theory ( lswt ), which is based on a localized spin picture and itinerant time - dependent density functional perturbation theory ( td - dfpt ), we investigate the spin fluctuation spectra of altermagnetic crsb. along the l - $ \ gamma $ - l $ ^ { \ prime } $ path, the lswt provides a chiral magnon splitting of up to 9 mev, located at high excitation energies around 140 mev, which is identified to be primarily driven by the splitting of two long - range exchange interactions, with exchange paths along the body diagonal lines of the unit cell. on the other hand, the more realistic td - dfpt obtains more significant splitting of $ \ sim $ 30 mev at maximum. however, the splitting is severely smeared out due to strong landau damping from the stoner continuum, which may make it difficult to observe experimentally, e. g. through inelastic neutron scattering. we further provide a brief discussion on the connection between the stoner excitations and the chiral magnon splitting.
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arxiv:2503.12920
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in federated learning ( fl ), a global model is trained at a parameter server ( ps ) by aggregating model updates obtained from multiple remote learners. generally, the communication between the remote users and the ps is rate - limited, while the transmission from the ps to the remote users are unconstrained. the fl setting gives rise to the distributed learning scenario in which the updates from the remote learners have to be compressed so as to meet communication rate constraints in the uplink transmission toward the ps. for this problem, one wishes to compress the model updates so as to minimize the loss in accuracy resulting from the compression error. in this paper, we take a rate - distortion approach to address the compressor design problem for the distributed training of deep neural networks ( dnns ). in particular, we define a measure of the compression performance under communication - rate constraints - - the \ emph { per - bit accuracy } - - which addresses the ultimate improvement of accuracy that a bit of communication brings to the centralized model. in order to maximize the per - bit accuracy, we consider modeling the dnn gradient updates at remote learners as a generalized normal distribution. under this assumption on the dnn gradient distribution, we propose a class of distortion measures to aid the design of quantizers for the compression of the model updates. we argue that this family of distortion measures, which we refer to as " $ m $ - magnitude weighted $ l _ 2 $ " norm, captures the practitioner ' s intuition in the choice of gradient compressor. numerical simulations are provided to validate the proposed approach for the cifar - 10 dataset.
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arxiv:2202.02812
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recently, electrides have received increasing attention due to their multifunctional properties as superconducting, catalytic, insulating, and electrode materials, with potential to offer other performance and possess novel physical states. this work uncovers that li $ _ 5 $ n as an electride possess four novel physical states simultaneously : electride state, super - coordinated state, superconducting state, and superionic state. by obtaining high - pressure phase diagrams of the li - n system at 150 - 350 gpa using a crystal structure search algorithm, we find that li $ _ 5 $ n can remain stable as p6 / mmm structure and has a 14 - fold super - coordination number, as verified by bader charge and electron localization function analysis. aditionally, we find that its superconducting transition temperature decreases continuously with increasing pressure, contrary to the behavior of most high - pressure superconducting materials. its superconducting transition temperature reaches the highest among all known electride at 150 gpa ( tc = 48. 97 k ). besides, li $ _ 5 $ n exhibits the superionic state at 3000 k, in which n atoms act like solid, while some li atoms flow like liquid. the above results are further verified at a macroscopic level by using deep learning potential molecular dynamics simulations.
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arxiv:2205.15002
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astronomical observations reveal hierarchical structures in the universe, from galaxies, groups of galaxies, clusters and superclusters, to filaments and voids. on the largest scales it seems that some kind of statistical homogeneity can be observed. as a result, modern cosmological models are based on spatially homogeneous and isotropic solutions of the einstein equations, and the evolution of the universe is approximated by the friedmann equations. in parallel to standard homogeneous cosmology, the field of inhomogeneous cosmology and backreaction is being developed. this field investigates whether small scale inhomogeneities via non - linear effects can backreact and alter the properties of the universe on its largest scales, leading to a non - friedmannian evolution. this paper presents the current status of inhomogeneous cosmology and backreaction. it also discusses future prospects of the field of inhomogeneous cosmology, which is based on a survey of 50 academics working in the field of inhomogeneous cosmology.
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arxiv:1612.08222
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we introduce the concept of valley - layer coupling ( vlc ) in two - dimensional materials, where the low - energy electronic states in the emergent valleys have valley - contrasted layer polarization such that each state is spatially localized on the top or bottom super - layer. the vlc enables a direct coupling between valley and gate electric field, opening a new route towards electrically controlled valleytronics. we analyze the symmetry requirements for the system to host vlc, demonstrate our idea via first - principles calculations and model analysis of a concrete 2d material example, and show that an electric, continuous, wide - range, and switchable control of valley polarization can be achieved by vlc. furthermore, we find that systems with vlc can exhibit other interesting physics, such as valley - contrasting linear dichroism and optical selection of the electric polarization of interlayer excitons.
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arxiv:1904.06498
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this paper presents a method for time series forecasting with deep learning and its assessment on two datasets. the method starts with data preparation, followed by model training and evaluation. the final step is a visual inspection. experimental work demonstrates that a single time series can be used to train deep learning networks if time series in a dataset contain patterns that repeat even with a certain variation. however, for less structured time series such as stock market closing prices, the networks perform just like a baseline that repeats the last observed value. the implementation of the method as well as the experiments are open - source.
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arxiv:2302.12027
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we study network properties of networks evolving in time based on optimal transport principles. these evolve from a structure covering uniformly a continuous space towards an optimal design in terms of optimal transport theory. at convergence, the networks should optimize the way resources are transported through it. as the network structure shapes in time towards optimality, its topological properties also change with it. the question is how do these change as we reach optimality. we study the behavior of various network properties on a number of network sequences evolving towards optimal design and find that the transport cost function converges earlier than network properties and that these monotonically decrease. this suggests a mechanism for designing optimal networks by compressing dense structures. we find a similar behavior in networks extracted from real images of the networks designed by the body shape of a slime mold evolving in time.
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arxiv:2109.00971
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koch and oesterreicher ' s model of " n \ " ahe und distanz " ( n \ " ahe = immediacy, conceptual orality ; distanz = distance, conceptual literacy ) is constantly used in german linguistics. however, there is no statistical foundation for use in corpus linguistic analyzes, while it is increasingly moving into empirical corpus linguistics. theoretically, it is stipulated, among other things, that written texts can be rated on a scale of conceptual orality and literacy by linguistic features. this article establishes such a scale based on pca and combines it with automatic analysis. two corpora of new high german serve as examples. when evaluating established features, a central finding is that features of conceptual orality and literacy must be distinguished in order to rank texts in a differentiated manner. the scale is also discussed with a view to its use in corpus compilation and as a guide for analyzes in larger corpora. with a theory - driven starting point and as a " tailored " dimension, the approach compared to biber ' s dimension 1 is particularly suitable for these supporting, controlling tasks.
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arxiv:2502.03252
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we present a dynamical model describing how halo particles can receive a significant energy kick from the merger between their own host halo and a target halo. this is highly relevant for understanding the growth of cosmological halos, and could especially provide an explanation for some high velocity objects. the model we present includes a \ emph { double scattering mechanism }, where a halo particle is given a significant energy kick by undergoing two subsequent gravitational deflections during the merger. the first deflection is by the potential of the target halo, whereas the second is by the potential of the particle ' s original host halo. the resultant energy kick arises because the two halos move relative to each other during the two deflections. to our knowledge, this mechanism has never been characterized in this context before. we derive analytically a halo particle ' s total kick energy, which is composed of energy from the double scattering mechanism and energy release from tidal fields, as a function of its position in its original host halo. in the case of a $ 1 : 10 $ merger between two hernquist halos, we estimate that the presented mechanisms can generate particles with a velocity $ \ sim 2 $ times the virial velocity of the target halo measured at its virial sphere. this motivates us to suggest that the high velocity of the recently discovered globular cluster hvcg - 1 \ citep { 2014apj... 787l.. 11c } can be explained by a head - on halo merger. finally, we illustrate the orbital evolution of particles outside the virial sphere of the target halo, by solving the equation of motion in an expanding universe. we find a ' sweet spot ' around a scale factor of $ 0. 3 - 0. 5 $ for ejecting particles into large orbits, which easily can reach beyond $ \ sim 5 $ virial radii.
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arxiv:1409.4421
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we take advantage of gravitational lensing amplification by abell 1689 ( z = 0. 187 ) to undertake the first space - based census of emission line galaxies ( elgs ) in the field of a massive lensing cluster. forty - three elgs are identified to a flux of i _ 775 = 27. 3 via slitless grism spectroscopy. one elg ( at z = 0. 7895 ) is very bright owing to lensing magnification by a factor of ~ 4. 5. several balmer emission lines detected from ground - based follow - up spectroscopy signal the onset of a major starburst for this low - mass galaxy ( m _ * = 2 x 10 ^ 9 solar masses ) with a high specific star formation rate ( ~ 20 / gyr ). from the blue emission lines we measure a gas - phase oxygen abundance consistent with solar ( 12 + log ( o / h ) = 8. 8 + / - 0. 2 ). we break the continuous line - emitting region of this giant arc into seven ~ 1kpc bins ( intrinsic size ) and measure a variety of metallicity dependent line ratios. a weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. interestingly, the metal line ratios in a region offset from the center by ~ 1kpc have a placement on the blue hii region excitation diagram with f ( [ oiii ] ) / f ( hbeta ) and f ( [ neiii ] ) / f ( hbeta ) that can be fit by an agn. this asymmetrical agn - like behavior is interpreted as a product of shocks in the direction of the galaxy ' s extended tail, possibly instigated by a recent galaxy interaction.
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arxiv:1205.2795
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let \ fc be a holomorphic foliation by riemann surfaces defined on a compact complex projective surface x satisfying the following two conditions : ( 1 ) the singular points of \ fc are all hyperbolic ; ( 2 ) \ fc is brody hyperbolic. then we establish cohomological formulas for the lyapunov exponent and the poincar \ ' e mass of an extremal positive \ ddc - closed current tangent to \ fc. if, moreover, there is no nonzero positive closed current tangent to \ fc, then we show that the lyapunov exponent \ chi ( \ fc ) of \ fc, which is, by definition, the lyapunov exponent of the unique normalized positive \ ddc - closed current tangent to \ fc, is a strictly negative real number. as an application, we compute the lyapunov exponent of a generic foliation with a given degree in $ \ mathbb p ^ 2. $
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arxiv:1812.10125
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the unmanned aerial vehicle ( uav ) - enabled communication technology is regarded as an efficient and effective solution for some special application scenarios where existing terrestrial infrastructures are overloaded to provide reliable services. to maximize the utility of the uav - enabled system while meeting the qos and energy constraints, the uav needs to plan its trajectory considering the dynamic characteristics of scenarios, which is formulated as the markov decision process ( mdp ). to solve the above problem, a deep reinforcement learning ( drl ) - based scheme is proposed here, which predicts the trend of the dynamic scenarios to provide a long - term view for the uav trajectory planning. simulation results validate that our proposed scheme converges more quickly and achieves the better performance in dynamic scenarios.
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arxiv:2209.08235
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we have investigated the electronic structure of fluorite cu $ _ { 2 } $ se using density functional theory calculations within the lda, pbe and am05 approximations as well as with the non - local hybrid pbe0 and hse approximations. our results show that cu $ _ { 2 } $ se is a zero gap semiconductor when using either a local or semi - local density functional approximation while there exists a gap when using the pbe0 functional. for the hse approximation, we find that the presence of a gap depends on the range separation for the non - local exchange within the hse approximation. for the occupied states we find that the lda, pbe, am05, pbe0 and hse agrees when regarding the overall structure, however, the hybrid functionals are shifted towards lower energy values compared to the lda, pbe and am05. the valence bands obtained using the hybrid functionals are in good agreement with experimental valence band spectra. we also find that the pbe, pbe0 and hse approximations give similar results regarding bulk properties, such as lattice constants and bulk modulus. in addition, we have investigated the localization of the cu d - states and its effect on the band gap in the material using the lda + u approach. we find that a gap is opened up by increasing the $ u $, however, the $ u $ values required for a gap opening is unrealistically high.
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arxiv:1211.0410
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we establish an upper bound of the bottom of the essential spectrum for the generator associated with a regular dirichlet form in terms of the rates of the volume growth / decay and big jump. using this bound, we discuss how the bottom of the essential spectrum is affected by the volume growth and coefficient growth.
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arxiv:2503.22899
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the coming flavour precision era will allow to uncover various patterns of flavour violation in different new physics scenarios. we discuss different classes of them. a simple extension of the standard model that generally introduces new sources of flavour and cp violation as well as right - handed currents is the addition of a u ( 1 ) gauge symmetry to the sm gauge group. in such z ' models correlations between various flavour observables emerge that could test and distinguish different z ' scenarios. a concrete model with flavour violating z ' couplings is the 331 model based on the gauge group su ( 3 ) _ c x su ( 3 ) _ l x u ( 1 ) _ x. we also study tree - level fcncs mediated by heavy neutral scalars and / or pseudo - scalars h ^ 0 ( a ^ 0 ). furthermore the implications of an additional approximate global u ( 2 ) ^ 3 flavour symmetry is shortly discussed. finally a model with vectorlike fermions and flavour violating z couplings is presented. we identify a number of correlations between various observables that differ from those known from constrained minimal flavour violating ( cmfv ) models and that could test and distinguish these different scenarios.
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arxiv:1305.4771
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wi - fi technology is continuously innovating to cater to the growing customer demands, driven by the digitalisation of everything, both in the home as well as the enterprise and hotspot spaces. in this article, we introduce to the wireless community the next generation wi - fi $ - $ based on ieee 802. 11be extremely high throughput ( eht ) $ - $, present the main objectives and timelines of this new 802. 11be amendment, thoroughly describe its main candidate features and enhancements, and cover the important issue of coexistence with other wireless technologies. we also provide simulation results to assess the potential throughput gains brought by 802. 11be with respect to 802. 11ax.
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arxiv:1902.04320
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a weighted automaton is functional if any two accepting runs on the same finite word have the same value. in this paper, we investigate functional weighted automata for four different measures : the sum, the mean, the discounted sum of weights along edges and the ratio between rewards and costs. on the positive side, we show that functionality is decidable for the four measures. furthermore, the existential and universal threshold problems, the language inclusion problem and the equivalence problem are all decidable when the weighted automata are functional. on the negative side, we also study the quantitative extension of the realizability problem and show that it is undecidable for sum, mean and ratio. we finally show how to decide whether the language associated with a given functional automaton can be defined with a deterministic one, for sum, mean and discounted sum. the results on functionality and determinizability are expressed for the more general class of functional group automata. this allows one to formulate within the same framework new results related to discounted sum automata and known results on sum and mean automata. ratio automata do not fit within this general scheme and different techniques are required to decide functionality.
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arxiv:1111.0862
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we review the features of the pomeron in the s - matrix theory and in quantum field theory. we extend those general properties to the pomeron of closed bosonic string theory in a minkowskian background. we compute the couplings of the pomeron to the lowest mass levels of closed bosonic string states in flat space. we recognize the deviation from the linearity of the regge trajectories in a five dimensional anti de sitter background.
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arxiv:1002.4028
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we have synthesized two nb @ c composites with an order of magnitude difference in the density of single - atom niobium substituted into graphitic layers. the concentration and sites of single - atom nb are identified using aberration - corrected scanning transmission electron microscopy and density functional theory. comparing the complex permittivity spectra show that the representative dielectric resonance at ~ 16 ghz originates from the intrinsic polarization of single - atom nb sites, confirmed by theoretical simulations. the single - atom dielectric resonance represents the physical limit of the electromagnetic response of condensed matter, and thus might open up a new avenue for designing electromagnetic wave absorption materials. single - atom resonance also has important implications in understanding the correlation between the macroscopic dielectric behaviors and the atomic - scale structural origin.
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arxiv:1507.01557
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we examine bounds on adiabatic and isocurvature density fluctuations from $ \ mu $ - type spectral distortions of the cosmic microwave background ( cmb ). studies of such distortion are complementary to cmb measurements of the spectral index and its running, and will help to constrain these parameters on significantly smaller scales. we show that a detection on the order of $ \ mu \ sim 10 ^ { - 7 } $ would strongly be at odds with the standard cosmological model of a nearly scale - invariant spectrum of adiabatic perturbations. further, we find that given the current cmb constraints on the isocurvature mode amplitude, a nearly scale - invariant isocurvature mode ( common in many curvaton models ) cannot produce significant $ \ mu $ - distortion. finally, we show that future experiments will strongly constrain the amplitude of the isocurvature modes with a highly blue spectrum as predicted by certain axion models.
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arxiv:1202.6066
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we have observed an anomalous shift of the high field reentrant insulating phases in a two - dimensional electron system ( 2des ) tightly confined within a narrow gaas / algaas quantum well. instead of the well - known transitions into the high field insulating states centered around $ \ nu = 1 / 5 $, the 2des confined within an 80 \ aa - wide quantum well exhibits the transition at $ \ nu = 1 / 3 $. comparably large quantum lifetime of the 2des in narrow well discounts the effect of disorder and points to confinement as the primary driving force behind the evolution of the reentrant transition.
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arxiv:cond-mat/0302467
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enabling autonomous robots to operate robustly in challenging environments is necessary in a future with increased autonomy. for many autonomous systems, estimation and odometry remains a single point of failure, from which it can often be difficult, if not impossible, to recover. as such robust odometry solutions are of key importance. in this work a method for tightly - coupled lidar - radar - inertial fusion for odometry is proposed, enabling the mitigation of the effects of lidar degeneracy by leveraging a complementary perception modality while preserving the accuracy of lidar in well - conditioned environments. the proposed approach combines modalities in a factor graph - based windowed smoother with sensor information - specific factor formulations which enable, in the case of degeneracy, partial information to be conveyed to the graph along the non - degenerate axes. the proposed method is evaluated in real - world tests on a flying robot experiencing degraded conditions including geometric self - similarity as well as obscurant occlusion. for the benefit of the community we release the datasets presented : https : / / github. com / ntnu - arl / lidar _ degeneracy _ datasets.
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arxiv:2403.05332
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in this paper, we investigate new integrable extensions of two - center coulomb systems. we study the most general $ n $ - dimensional deformation of the two - center problem by adding arbitrary functions supporting second order commuting conserved quantities. the system is superintegrable for $ n > 4 $ and, for certain choices of the arbitrary functions, reduces to known models previously discovered. then, based on this extended system, we introduce an additional integrable generalisation involving calogero interactions for $ n = 3 $. in all examples, including the two - center problem, we explicitly present the complete list of liouville integrals in terms of second - order integrals of motion.
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arxiv:2312.02013
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